By population, Mexico City is the third largest city in the world, sent into the record books by a massive greater metropolitan area, that has a population exceeding 19 million people. The municipality of Xico is part of the Mexico City metropolitan area, marking the very edge of the city’s southernmost reach. It is at this point that the city has begun to make a slight detour, around Cerro de Xico (Xico hill). It should be obvious that this isn’t just a hill of course – it’s a beautifully round volcanic crater; one that is in the process…